VM Storage Performance

The intensified demand for IT network efficiency, increased application performance
and lower operating costs have been driving the phenomenal growth of virtualization
in the past decade, with no signs of slowing. At present, many organizations run
more virtual servers than physical servers.

In order to understand VM storage performance, we first need to
understand what storage virtualization is. Storage virtualization involves the creation
of a usually very large, logical-pool of data. Via software, that pool appears to
be physically located all on one server. In actuality, that data may be located
across hundreds of physical disks spread across dozens of servers. This is the concept
implemented by Storage Area Networks (SAN).

This technology essentially abstracts "logical storage" (what the OS sees and uses
– i.e., the file system) from physical storage (the striped RAID sets). The key
differentiator in virtual storage is that the multiple physical storage devices
(e.g. a RAID array) are combined into one large grouping, on top of which a virtual
storage container is created.

V-locity® is "set and forget" I/O optimization software that allows IT
organizations to go faster than ever before in virtualized environments without
the cost of new or additional storage hardware. By optimizing reads and writes,
V-locity improves VM performance by up to 50%, eliminating application bottlenecks
and enabling more VMs on a single, physical server.

In order to better accommodate disk I/O, most virtualization platforms will implement
a Storage Area Network (SAN) which can offer greater data throughput, and a dynamic
environment to address fluctuations in I/O demands.

While a storage infrastructure can be built out to meet expected demands, there
are behaviors that will still impede performance.

One such behavior is unnecessary I/O created by the Windows OS at the time files
are written. As files are written to general purpose local disk file systems, such
as Windows NTFS, an inherent byproduct is unnecessary I/O due to files being split
apart—a state in in which the data stream of a file is stored in non-contiguous
clusters in the file system. This occurs on the logical volume, translated to logical
blocks, and eventually to physical sectors residing on a storage device. It can
be demonstrated as pieces of a file located in a non-contiguous manner. The effect
of this is increased I/O overhead, leading to slower system performance for the
operating system.

In the case of virtual platforms, a guest operating system is stored as a file (i.e.,
set of files) on the virtual platforms file system as a “virtual disk.” A virtual
disk is essentially a container file, housing all the files that constitute the
OS and user data of a VM.

Eliminating unnecessary I/O in the virtual environment is vital to platform-wide
VM storage performance and enhances the ability to host more VMs on a shared infrastructure.
Installing V-locity in a virtual environment
will enormously improve the application and storage performance of all VMware ESX/ESXi
and Microsoft Hyper-V virtual platforms automatically, intelligently and cost effectively.